1. Field of the Invention
The present invention relates to a clean room for manufacturing of semiconductor device having installed manufacturing facilities such as variety of manufacturing apparatuses and measuring apparatuses used to manufacture the semiconductor devices.
2. Description of the Related Art
Semiconductor devices are manufactured, as is well known, within a clean room having installed various manufacturing apparatuses used in various manufacturing processes (wet process, dry process, oxidation, lithography, ion implantation, etc.) and measuring apparatuses used for various measuring processes in testing for quality control. Examples of such clean room is described in the reference 1, CLEAN TECHNOLOGY, published by Japan Industrial Publication Inc., 1997, Vol. 7, No. 1 and the reference 2, Japan 300 mm Semiconductor Technology Conference (J300), 1996, December 3, 2nd Lecture "ICs Factory Design for 300 mm Wafer Line Standardizing Study P9 to 10".
In such a clean room, the manufacturing apparatuses and measuring apparatuses are usually installed. In other words, an automatic transferring system is installed for transferring precursors such as wafers which are uncompleted semiconductor devices between these manufacturing facilities.
FIG. 1A and FIG. 1B respectively show examples of clean rooms to which the automatic transferring system of this type has been introduced. In these figures, the reference numeral 1 denotes a clean room. In this clean room 1, many manufacturing facilities, each of which is composed of the manufacturing apparatuses and measuring apparatuses, are provided as shown in the plan view of FIG. 1A and a clean bay 3, which is the space allowing a worker to walk through and work therein, is provided in the front side of the manufacturing facility 2, namely in the precursor take-in/take-out side (not illustrated).
In this clean room 1, an air filter 4 is provided at the ceiling area as shown in the side sectional view of FIG. 1B, thereby the clean air is supplied, by means of a fan not illustrated, to the manufacturing space 5 in the clean room 1 passing through the air filter 4 from the rear side of the ceiling area, moreover the clean air having passed the manufacturing space 5 is caused to flow into an air returning area 6 under the floor passing through a ventilation aperture (not illustrated) formed at the floor and this air is circulated again to the rear side of the ceiling by means of the fan.
In such a clean room 1, the automatic transferring system described previously is composed of an overhead rail running type transferring apparatus and an Automated Guided Vehicle (AGV) 7. As shown in FIG. 1A and FIG. 1B, the overhead rail running type transferring apparatus is provided to transfer the precursors between the clean bays 3, 3, namely between the processes. This transferring apparatus is composed, as shown in FIG. 1B, of a running rail 8 provided high in the ceiling side and a carrier 9 running on this rail 8. The automated guided vehicle 7 travels, as shown in FIG. 1A, the route to reciprocally move the clean bay 3 from the side of the running rail 8, namely transfers the precursors within the process.
In addition, as shown in FIG. 1A, in such automatic transferring system, a stocker 10 is also arranged at the area just under the running rail 8 in order to once stock the precursors before having over the precursors to the automated guided vehicle 7 from the carrier 9.
In regard to manufacturing of semiconductor devices, small-kind and large-lot production system tends to be changed to the multi-kind and small-lot production system in recent years and the wafers are recently processed in unit of a small lot because the wafer diameter is increased and moreover a request for short TAT (Turn Around Time) is raised and thereby the precursors are recently transferred in a small lot. As explained above, since the precursors are transferred in a small lot, the transfer frequency of the precursors in the clean room 1 is also increasing in these years.
Therefore, various methods are attempted to enhance the transferring capability responding to increase of transfer frequency and the request for short TAT. For example, in order to enhance the transferring capability, it has been attempted that the running rail 8 is doubled or quadrupled or more multiplexed to realize multiple transfer loop of the running rail 8. Moreover in order to enhance the transferring capability in the process, it has also been attempted that a high speed automated guided vehicle is introduced.
However, enhancement of the transferring capability is more and more required under the condition that the requirement for short TAT is still further increased.
But, since the precursors are transferred through the running of the automated guided vehicle 7 and the carrier 9 within the manufacturing space 5 where many manufacturing facilities 2 are installed, the automatic transferring system of the related art cannot shorten the transferring distance due to limitation in the transfer route and moreover is difficult to further enhance its transferring capability because occupied area of the automatic transferring system in the clean room 1 is increasing.